Hi Jeremy,
I did figure out the SQL query to achieve my need.
However, as a newbie to Sequel, I do not know how to turn it into a Sequel DSL
though
Below is my SQL query:
```
select models.id
,case
when (select max(events.created_at) from events where
event_type='DoSomething' and models.id = events.model_id) is not null
and
(select max(events.created_at) from events where event_type='UndoSomething'
and models.id = events.model_id) is null
then true
when (select max(events.created_at) from events where
event_type='DoSomething' and models.id = events.model_id)
>
(select max(events.created_at) from events where event_type='UndoSomething'
and models.id = events.model_id)
then true
else false
end as did_something
from models;
```
In Model I have tried
```
def with_did_something
select(:models,
Sequel.case([
[select(:events).where(:event_type => ‘DoSomething’, :models__id =>
:events__model_id).max(:events__created_at)
>
select(:events).where(:event_type => ‘UndoSomething’, :models__id =>
:events__model_id).max(:events__created_at)],
true
], false).as(:did_something)
)
end
```
Of course it will not work because `select(:events)` in `dataset_module` will
become `select events from leads` SQL.
If you can, could you please give me a hint? Thank you
Cheers,
Bang
> On 29 Apr 2016, at 8:03 AM, Jeremy Evans <[email protected]> wrote:
>
> On Wednesday, April 27, 2016 at 6:13:42 AM UTC-7, The Bang Nguyen wrote:
> Hi Jeremy,
>
> I thought I got your idea, but I did not.
> Sorry for bothering you again.
>
> >do_something = event_ds.where(:event_type=>'do_something').max(:created_time)
> If there is any `event` with `event_type` is `do_something`, do_something
> will always be not nil.
> Thus `did_something` will be always true.
>
> For example:
> Lets say I have 2 `model`(s).
> First one have `event` with `event_type` is `do_something`. Second one does
> not have any event.
> With your code, I will receive dataset in which both `did_something` for 2
> `model` are `true`.
>
> My expectation is to get back the dataset in which `did_something` for first
> `model` is `true` and second one is `false`
>
> Ah, then you'd probably have to select a CASE expression with a subquery
> using similar logic as my earlier example. Try giving that a shot. If you
> can't get it to work, please post here with your attempt.
>
> Thanks,
> Jeremy
>
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